1. Field of the Invention
The present invention relates to a negative differential resistance element, particularly to such an element having three terminals and which can be modulated externally.
2. Description of the Related Art
Known in the prior art are negative differential resistance elements, such as a degenerated p-n junction diode (Esaki diode), AlGaAs/GaAs heterojunction diode using resonant tunneling (R. Tsu and L. Esaki, "Tunneling in a finite superlattice", Applied Physics Letters, 22 (1973) p562), and a resonance diode with a potential barrier of AlGaAs/GaAs (Yasuhito Zohta, "Negative resistance of semiconductor heterojunction diodes owing to transition resonance" J. Appl. Phys. 57(6), Mar. 15, 1985, pp. 2234-2236) These negative differential resistance elements have two terminals and fixed characteristics, and can not be modulated externally.
Also known is a resonant-tunneling hot electron transistor (RHET) in which electrons are injected from emitter to base by resonant-tunneling through a quantum well (Naoki Yokoyama, etc. "A New Functional, Resonant-Tunneling Hot Electron Transistor (RHET)", Japanese Journal of Applied Physics, Vol. 24, No. 11, November, 1985, pp. L853-L854). This device shows a peaked collector-current characteristic with respect to the base-emitter voltage, i.e., a negative differential resistance. Another example is a three terminal, negative differential-resistance device using real-span-transfer (A. Kastalsky et al. "A Field-Effect Transistor with a Negative Differential Resistance").